From b3a43d137c6c9ecf271a2a3d51a51b2fd1c3e8f6 Mon Sep 17 00:00:00 2001
From: Laramie Leavitt <laramiel@users.noreply.github.com>
Date: Fri, 18 Mar 2022 11:10:31 -0700
Subject: [PATCH] Use rvalue reference for std::variant cast_op<T> (#3811)

Nearly every call site of cast_op<T> uses an r-value reference.

Except stl.h variant_caster::load_alternative for handling std::variant.

Fix that.
---
 include/pybind11/stl.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/pybind11/stl.h b/include/pybind11/stl.h
index b66129688..e3a061444 100644
--- a/include/pybind11/stl.h
+++ b/include/pybind11/stl.h
@@ -372,7 +372,7 @@ struct variant_caster<V<Ts...>> {
     bool load_alternative(handle src, bool convert, type_list<U, Us...>) {
         auto caster = make_caster<U>();
         if (caster.load(src, convert)) {
-            value = cast_op<U>(caster);
+            value = cast_op<U>(std::move(caster));
             return true;
         }
         return load_alternative(src, convert, type_list<Us...>{});